A large variety of products useful, for instance, as nonionic surfactants, wetting and emulsifying agents, solvents and chemical intermediates are prepared by the addition reaction (alkoxylation reaction) of alkylene oxides (epoxides) with organic compounds having one or more active hydrogen atoms. For example, particular mention may be made of the alcohol ethoxylates prepared by the reaction of ethylene oxide with aliphatic alcohols of 6 to 30 carbon atoms. Such ethoxylates, and to a lesser extent corresponding propoxylates and compounds containing mixed oxyethylene and oxypropylene groups, are widely employed as nonionic detergent components in cleaning and personal care formulations.
An illustration of the preparation of an alkanol ethoxylate (represented by formula III below) by addition of a number (n) of ethylene oxide molecules (formula II) to a single alkanol molecule (formula I) is presented by the equation:

One typical method of preparing such alkoxylated alcohols is by hydroformylating an olefin into an oxo-alcohol, followed by alkoxylation of the resulting alcohol by reaction with a suitable alkylene oxide such as ethylene oxide or propylene oxide.
Typically the olefin to be hydroformylated is obtained by the oligomerization of ethylene, for example as is used in the Shell Higher Olefin Process (SHOP).
Hydroformylation is typically conducted in the presence of a homogeneous catalyst which is based on a source of a transition metal, typically a metal of Group 8 (iron, ruthenium or osmium), 9 (cobalt, rhodium or iridium) or 10 (nickel, palladium or platinum) of the Periodic Table of Elements. In their catalytically active form these metals may be used with carbonyl ligands, but they can also be used as a complex with other ligands, suitably phosphorus-containing ligands. Such catalysts are commonly referred to as phosphine and/or phosphite-modified hydroformylation catalysts.
The first stage of the hydroformylation reaction is formation of an oxo-aldehyde. This is followed by a secondary reaction involving the hydrogenation of the oxo-aldehyde into the corresponding oxo-alcohol. The secondary reaction may occur simultaneously with the actual hydroformylation reaction, depending on the type of catalyst used. Some of the homogeneous hydroformylation catalysts are sufficiently active to hydrogenate the in-situ formed oxo-aldehyde into the desired oxo-alcohol. Sometimes, however, a separate hydrofinishing step is applied in order to improve the quality of the final oxo-alcohol product in terms of its aldehyde content.
Once the oxo-alcohols have been alkoxylated, they may be used as nonionic surfactants in a wide variety of products, such as, for example, detergent compositions, lubricants and personal care compositions. Especially useful for this purpose are ethoxylated and/or propoxylated alcohols which contain from 9 to 17 carbon atoms in the carbon backbone, excluding the carbon atoms in ethoxy/propoxy groups.
As can be seen from the above discussion, current commercial processes for producing ethoxylated alcohols involve multi-step processes, for example involving the following steps (1)–(3): (1) oligomerization of ethylene to produce an olefin, (2) hydroformylation of the olefin to produce an alcohol, and (3) alkoxylation of the alcohol to produce an alkoxylated alcohol. Further, currently used processes for producing alkoxylated alcohols are based on ethylene feedstocks, which tend to be relatively expensive.
In view of the high demand in the detergents industry for nonionic alkoxylated alcohol surfactants, it would be desirable to provide a less complex process for preparing alkoxylated alcohols. At the same time, it would be desirable to make use of feedstocks which are cheaper than ethylene. In particular, it would be desirable to make use of feedstocks derived from the “Fischer-Tropsch” hydrocarbon synthesis which involves the reaction of carbon monoxide and hydrogen (“synthesis gas”) to produce hydrocarbons. The synthesis gas used in the Fischer-Tropsch hydrocarbon synthesis is derived from cheap, abundantly available natural gas or coal.
In addition to hydrocarbons such as paraffins and olefins, feedstocks derived from the Fischer-Tropsch process typically also contain a certain amount of oxygenate components such as alcohols and aldehydes. The amount of alcohols present in the Fischer-Tropsch stream varies depending on the type of catalyst used, although it may be relatively low compared with the amount of hydrocarbons (e.g. paraffins). It has now surprisingly been found by the present inventors that despite the relatively low levels of alcohols present in feedstocks derived from the Fischer-Tropsch synthesis, these alcohols can be ethoxylated directly. This leads to a process for preparing ethoxylated alcohols which comprises fewer steps than current commercial processes. In addition, the process of the present invention enables the use of Fischer-Tropsch derived feedstocks that tend to be cheap relative to ethylene feedstocks and contain very low levels of sulphur and/or nitrogen contaminants.